The configuration of a general organic EL display panel having a top emission structure is shown in FIG. 5. FIG. 5(a) is a plan view of the general organic EL display panel having a top emission structure, and FIG. 5(b) is a sectional view taken along line A1-A1 in FIG. 5(a).
Generally, in an organic EL display panel having a top emission structure, a color filter 2 is placed on the lighting surface of an organic EL device 1. The lighting surface of the organic EL device is a surface from which light is emitted.
The organic EL device 1 has a structure in which a lower electrode 4 is provided on a substrate 3, and organic light emitting layers 6 in three primary colors are held between the lower electrode 4 and an upper electrode 7. The adjacent organic light emitting layers 6 are separated by light emitting layer partitions 5. Meanwhile, the color filter 2 has a structure in which a grid black matrix 9 is provided on a transparent substrate 8, and pigment layers 10 in three primary colors are placed in the frames of the black matrix 9. The color filter 2 is placed on the organic EL device 1 in a state where the surface of the color filter 2 on the side of the black matrix 9 faces the organic EL device 1. The transparent substrate 8 is, for example, a glass substrate.
The organic light emitting layers 6 in three primary colors include a red light emitting layer, a blue light emitting layer, and a green light emitting layer. The organic light emitting layers 6 in these colors are repeatedly placed in a first direction. The organic light emitting layers 6 in the same color are placed in a second direction perpendicular to the first direction. As shown in FIG. 5(a), the pigment layers 10 in three primary colors include a red pigment layer 10a, a blue pigment layer 10b, and a green pigment layer 10c. The pigment layers 10 in these colors are repeatedly placed in the first direction. The pigment layers 10 in the same color are placed in the second direction.
The pigment layers 10 in three primary colors are provided to adjust the chromaticity of light beams in three primary colors emitted from the organic light emitting layers 6 in three primary colors. The black matrix 9 is provided to prevent the color mixture of the light beams in three primary colors emitted from the organic light emitting layers 6 in three primary colors. The black matrix 9 and the pigment layers 10 are provided over an effective pixel area that displays images in an organic EL display panel.
The organic EL device 1 and the color filter 2 are bonded by a transparent resin 11. With the transparent resin 11, the light beams in three primary colors emitted from the organic light emitting layers 6 reach the pigment layers 10 without a reduction in the amount of light. The transparent resin 11 also has a function of protecting the organic light emitting layers 6 from being deteriorated by oxygen or water.
In the organic EL display panel, in order to prevent color shading, the thickness of the transparent resin 11, which determines a distance between the organic light emitting layer 6 in the organic EL device 1 and the pigment layer 10 in the color filter 2, needs to be set within a predetermined acceptable range.
For example, Patent Literature 1 has proposed a technique of setting the thickness of the transparent resin 11 by, as shown in FIG. 6, diffusing and mixing spherical spacers 12 in a transparent resin layer. FIG. 6 shows the configuration of a conventional organic EL display panel in which the spherical spacers are diffused and mixed in the transparent resin layer. Specifically, FIG. 6(a) is a plan view of the organic EL display panel, FIG. 6(b) is a sectional view taken along line A2-A2 in FIG. 6(a), and FIG. 6(c) is a sectional view taken along line A3-A3 in FIG. 6(a). In FIG. 6, the same components as those in FIG. 5 are denoted by the same reference numerals.
Further, for example, Patent Literature 2 has proposed another technique of setting the thickness of the transparent resin 11 by, as shown in FIG. 7, providing a rod-like spacer 13 between the organic EL device 1 and the color filter 2. FIG. 7 shows the configuration of a conventional organic EL display panel in which the rod-like spacer is provided between the organic EL device and the color filter. Specifically, FIG. 7(a) is a plan view of the organic EL display panel, FIG. 7(b) is a sectional view taken along line A4-A4 in FIG. 7(a), and FIG. 7(c) is a sectional view taken along line A5-A5 in FIG. 7(a). In FIG. 7, the same components as those in FIG. 5 are denoted by the same reference numerals. The rod-like spacer 13 is provided on the color matrix 9.